Water, stream morphology and landscape : complex habitat determinants for the fire salamander Salamandra salamandra

Understanding the relationship between environmental features and species distribution is a key step for successful habitat conservation. In semiaquatic amphibians, the features of both breeding sites and the surrounding upland habitat can play important roles. We evaluated the relative role of (1) stream morphology, (2) biotic features of water, and (3) composition of landscape surrounding wetlands, for the distribution of the fire salamander, Salamandra salamandra. We determined the presence of larvae in 132 localities, and we used an information-theoretic approach to build species distribution models. We then used variance partitioning to evaluate the relative importance of environmental variables. A model including both stream and landscape features explained a large proportion of variation. Larvae were associated to heterogeneous and shallow streams, with scarce periphyton, rich macrobenthos communities characteristic of oligotrophic water, and surrounded by woodlands. Variance partitioning showed that stream morphology was the parameter with the largest independent effect, but most of variation was explained by the combined effect of multiple variables, suggesting a strong interplay among biotic and abiotic features in determining species distribution. The complementation between multiple elements, such as wetlands and landscape features, can be the key of a correct understanding of distribution of semi-aquatic amphibians.